Beet sugar factory

Sugar beet on heaps

After they are harvested, beet are transported to a factory. In the UK, beets are transported by a hauler, or by a tractor and a trailer by local farmers. Railways and boats are no longer used. In Ireland some beets were carried by rail, until the complete shutdown of Irish Sugar beet production in 2006. The Netherlands originally relied on boats, and by 2021 this way of transport made a comeback.[11]

A mode of transport that has almost disappeared is the transport of raw juice by pipeline. The concept is that one or more râperies first extract the raw juice from the sugar beet. The juice is then transported by pipeline to a central sugar factory. The Râperie de Longchamps in Belgium is the last remaining râperie in Europe.[12]

On arrival at the factory, each load is weighed and sampled at the tarehouse. The beet sample is checked for:

• soil tare – the amount of soil and other detritus from harvesting that is included in the load.
• crown tare – the amount of beet that forms the crown of the root. This has a lower sugar content than the rest of the root and has less value to the operator
• sugar content ("pol") – a measurement of the amount of sucrose in the crop
• nitrogen content – for recommending future fertilizer use to the farmer

From these elements, the actual sugar content of the load is calculated and the grower's payment determined.

The load is then tipped onto the reception area, typically a flat concrete pad. From there, the beet are moved into large heaps. When it is time to process them, the beet are moved into a central channel or gulley, and are washed towards the processing plant.

The next step of the actual production process is washing and scrubbing. This is done by moving the beet around in washing and scrubbing tanks not unlike a washing machine. However, the actual washing is caused by the friction of the sugar beets against each other. This removes sand and stones and other objects.[10]

The cleaned beets are then mechanically sliced into fine "v" cross-section strips, called cossettes.[10] The V-shape maximises the area of the slice while maintaining some rigidity to the cossette so it is not completely broken up in the diffuser.

The cossettes are then passed to a machine called a diffuser. Here hot water permeates them to extract the sugar content into a water solution, a process known as leaching. The diffusion process ends with two products: raw juice and beet pulp.[10]

Diffusers are long vessels of many metres in which the beet slices go in one direction while the hot water goes in the opposite direction ("counter current"). The movement may either be caused by a rotating screw moving the cossettes or the whole unit rotating in which case the water and cossettes move through internal chambers of the drum. The three common designs of diffuser are the horizontal rotating "RT" (named after Raffinerie Tirlemontoise the original manufacturer), inclined screw "DDS" (from the Danish company De Danske Sukkerfabrikker ), or vertical screw "Tower". Modern tower extraction plants have a processing capacity of up to 17,000 metric tons (16,700 long tons; 18,700 short tons) per day.[13] A less-common design uses a moving belt that carries the cossettes over a series of tanks. Water is pumped onto the top of the belt and passes through the cossettes into the tank below which it pumped over the next section. In all cases, the flow rates of cossettes and water are in the ratio one to two. Typically, cossettes take about 90 minutes to pass through the diffuser, the water only 45 minutes. These countercurrent exchange methods extract more sugar from the cossettes using less water than if they merely sat in a hot water tank. The liquid exiting the diffuser is called "raw juice". The colour of raw juice varies from black to a dark red depending on the amount of oxidation, which is itself dependent on diffuser design.

The used cossettes, now called beet pulp, exit the diffuser at about 95% moisture, but low sucrose content. Using screw presses, the wet pulp is then pressed down to 75% moisture. This recovers additional sucrose in the liquid pressed out of the pulp, and reduces the energy needed to dry the pulp. The liquid pressed out of the pulp is combined with the raw juice, or more often introduced into the diffuser at the appropriate point in the countercurrent process. The final byproduct, vinasse, is used as fertilizer or growth substrate for yeast cultures.

During diffusion, a portion of the sucrose breaks down into invert sugars. These can undergo further breakdown into acids. These breakdown products are not only losses of sucrose, but also have knock-on effects reducing the final output of processed sugar from the factory.[lower-alpha 1] To limit (thermophilic) bacterial action, the feed water may be dosed with formaldehyde and control of the feed water pH is also practiced. Attempts at operating diffusion under alkaline conditions have been made, but the process has proven problematic. The improved sucrose extraction in the diffuser is offset by processing problems in the next stages.

Dried sugar beet cossettes

The products of the diffusion step are beet pulp and raw juice. The beet pulp is generally used as livestock feed. It can be sold directly as "wet pulp" but wet pulp has high moisture and soon develops mould. Dried pulp has higher value whether sold as shreds or pelleted. Pulp can also be mixed with molasses during the drying process for higher nutrient content The raw juice moves to the next processing stages for removal of impurities and conversion to solid sugar.[10]

The raw juice first undergoes purification to remove impurities which affect white sugar recovery quantity and quality.[14] The steps commonly used for beet are carbonatation and sulphonation. Carbonatation uses milk of lime, an alkaline liquid produced from calcium hydroxide, together with carbon dioxide (the exhaust from the lime kiln that produces the lime) to precipitate impurities into a form that can be removed from the raw juice. In the carbonation step, proteins are coagulated, and the calcium carbonate forms solid particles which incorporate the coagulated materials, pieces of vegetable matter, and absorb some soluble impurities. The high alkalinity destroys monosaccharides and other compounds which are thermally unstable and would breakdown in subsequent processing steps.[15] The precipitate is removed by gravitation and filtration to leave a clear, lighter coloured alkaline (ph 8.4 to 9.4) liquid known as thin juice. Flocculants may be used in the process to speed separation of precipitate. Thin juice may then undergo a sulphonation step, in which sulfur dioxide is used to bleach this juice.[16]

The addition of milk of lime and carbon dioxide may be in sequential steps (DDS or RT) with pre-liming and primary and secondary carbonatation steps separated by filtration of precipitates or in a process where juice is continuous cycling through primary and secondary steps to build particle size with a clarifier and rotary filters to remove precipitate (Dorr Oliver).

The thin juice is concentrated by multi-effect evaporation to make a "thick juice", roughly 60% sucrose by weight. For more efficient scaling of the refining equipment to the beet processing stage, raw juice at around 70% dry solids can be stored and refined after the beet slicing campaign.[14]

In a beet sugar refinery the only outputs are white crystalline sugar and molasses; intermediate products in the process are recycled.

The crystallization process starts by loading vacuum boiling pans ("white pans") with standard liquor (a mixture of raw juice and low grade sugar). The liquor is heated under reduced pressure to supersaturation. Seed crystals are added to the pan to act as the basis for the formation of crystals.[17] The sucrose in the liquor crystallises on the seed; when the crystals in the pan have reached the desired size (around 0.5 mm[15]) the contents of the pan are emptied via a receiver tank into centrifuges to separate crystals from the remaining sugar liquor. The crystals are given a brief wash in the centrifuge. The remaining liquor ("high green", about 50% of the pan's contents[15]) which still contains significant amounts of sugar is then boiled again (in "raw pans") to produce more crystals but of a lower quality with more impurities and colour. The sugar from this boiling is separated in centrifuges and remelted to feed the first stage, the residual liquor ("low green") may be boiled again (in "after product" (AP) pans) to separate the last of the recoverable crystal sugar. The remaining liquor at this stage is known as beet molasses.[18][14] The AP sugar may be affinated with liquor to wash the crystals before remelting.

The white sugar from the pans is dried and cooled in granulators and sent to storage. From storage the sugar is graded to give consistent particle size distribution for sale. Sugar crystals outside the specification are returned to the pans for reprocessing. Further grades of sugar e.g. icing sugar/powdered sugar are produced by milling.

The molasses from sugar beet still contain a significant amount of sugar - typically around 50% sucrose by weight. The remainder of molasses is fructose and glucose produced as breakdown products of sucrose during processing and soluble anions and cations from the beet such as potassium, sodium, chlorides, and nitrogen compounds.

The Steffen Process was used to recover sucrose from molasses, so advanced beet sugar factories had a "Steffen house" next to the plant. Sucrose was precipitated as a calcium saccharate and filtered off.[18] During World War I, when imported potash from European sources was unavailable in the United States, "Steffen's wastewater" provided a good source, leading to a profitable income stream for a factory. The need disappeared immediately after the war.

In the 1950s, industrial fermentation advanced to produce monosodium glutamate (MSG), previously produced in Japan by the expensive racemization process. Beet sugar molasses, with a Corynebacterium (especially Corynebacterium glutamicum) and combined with penicillin or a surfactant to block biotin, produced MSG as a result, which effectively produced large profits from what was formerly waste.[19]

During the refining process, raw beet sugar requires much more lime for purification.[9] Carbonation-lime residue contains about 80% Calcium carbonate and is therefore used to improve agricultural land.

The beet-sugar molasses that remain from the crystallization phase are the most valuable byproduct. It can be sold on the yeast fermentation, pharmaceutical, and animal food markets.[20] The molasses can be added to the beet pulp before drying to give a higher value product.

When the factory has a Molasses Desugaring by chromatography (MDC) process, processing leads to two more by-products:[20]

• concentrated molasses solids (CMS), which contains mainly minerals and is usually sold to the animal feed industry.
• Betaine chiefly through chromatographic separation, using techniques such as the "simulated moving bed".

Under the patronage of Frederick William III of Prussia, Franz Karl Achard opened the world's first beet sugar factory in 1801, at Kunern, Silesia (now Konary, Poland).[22] The idea to produce sugar from beet was soon introduced to France, where Napoleon opened schools specifically for studying the plant. He also ordered that 28,000 hectares (69,000 acres) be devoted to growing sugar beet.[23] This was in response to British naval blockades of France during the Napoleonic Wars (and the reciprocal Continental System imposed by Napoleon), which limited cane sugar imports to Europe and ultimately stimulated the rapid growth of a European sugar beet industry.[23] [24] By 1840, about 5% of the world's sugar was derived from sugar beets, and by 1880, this number had risen more than tenfold to over 50%.[23] The sugar beet was introduced to North America after 1830, with the first commercial production starting in 1879 at a farm in Alvarado, California.[24][25] The sugar beet was also introduced to Chile by German settlers around 1850.[25]

French sugar beet mill in operation in the 1840s

The work of Achard soon attracted the attention of Napoleon, who appointed a commission of scientists to go to Silesia to investigate Achard's factory. Upon their return, two small factories were constructed near Paris. Although these factories were not altogether a success, the results attained greatly interested Napoleon. Thus, when two events, the blockade of Europe by the British Royal Navy and the Haitian Revolution, made the importation of cane sugar untenable, Napoleon seized the opportunity offered by beet sugar to address the shortage. In 1811, Napoleon issued a decree appropriating one million francs for the establishment of sugar schools, and compelling the farmers to plant a large acreage to sugar beets the following year. He also prohibited the further importation of sugar from the Caribbean effective in 1813.[26]

The number of mills increased considerably during the 1820s and 1830s, reaching a peak of 543 in 1837. The number was down to 382 in 1842, producing about 22.5 million kg of sugar during that year.[27]

Beet sugar factory in Groningen, The Netherlands

As a result of the French advances in sugar beet production and processing made during the Napoleonic Wars, the beet sugar industry in Europe developed rapidly. A new tax levied in Germany in 1810 prompted the experimentation to increase the sugar content of the beet. This was because the tax assessed the value of the sugar beet crop based on the unprocessed weight of the sugar beet rather than the refined sugar produced from them.[26][28] By 1812, Frenchman Jean-Baptiste Quéruel, working for the industrialist Benjamin Delessert, devised a process of sugar extraction suitable for industrial application. By 1837, France had become the largest sugar beet producer in the world, a position it continued to hold in the world even into 2010. By 1837, 542 factories in France were producing 35,000 tonnes of sugar. However, by 1880, Germany became the largest producer of sugar from sugar beet in the world, since the German factories processed most of the sugar beets grown in eastern France.[22]

By the 1850s, sugar beet production had reached Russia and Ukraine. This was made possible by the protection of the sugar beet industry by bounties, or subsidies, paid to beet sugar producers upon the export of their sugar by their respective governments.[26][29] The protection provided to the sugar beet industry by these bounties caused drastic damage to the cane sugar industry and their grip on the British sugar market. The result was a reduction in the production of cane sugar, molasses and rum until 1915.[26][30] During World War I, the widespread conflict destroyed large tracts of land that had served sugar beet producers and repurposed much of the remaining sugar beet land for grain production. This resulted in a shortage that revived the shrinking cane sugar industry.[26]

The sugar industry in the EU came under bureaucratic pressure in 2006 and ultimately resulted in the loss of 20,000 jobs, although many factories, as detailed in a later 2010 EU audit, were found to have been mistakenly shut down, as they were profitable without government intervention.[31] In 2021/2022 the European Union was a small net importer of sugar.[32]

Sugar factory in Lehi, Utah

In the 1820s, the abolitionists in New England wanted to abolish slavery by boycotting the products that were made by slaves. They started to import sugar from Asia (called "free sugar" because it was grown without slavery), but this sugar tasted "awful".[33] In order to overcome the problems of the "free sugar" from Asia, the "Beet Sugar Society of Philadelphia" was founded in 1836. It promoted cottage-produced beet sugar as an alternative to the slave-produced cane sugar from the West Indies.[34] All pre-1870 movement failed, primarily because it approached the subject with naïve optimism and without sufficient capital. An attempt in Utah by the LDS Church-owned Deseret Manufacturing Company in the 1850s was carefully planned and funded, but failed due to saline soil conditions.[35]

After many failures, E. H. Dyer acquired a defunct sugar factory in Alvarado, California (now Union City) in 1879, and succeeded in making sugar in commercially viable amounts. It was soon joined by the Western Beet Sugar Company in Watsonville[36] The Oxnard brothers brought sugar beet cultivation to the plains, when they opened a factory in Grand Island, Nebraska.[37] In Utah, Arthur Stayner and others were able to convince LDS Church leaders to support a second attempt.[38] It led to the Utah-Idaho Sugar Company, which had Dyer built its factory in Lehi, Utah in 1890.[39]

Capital investment in factories demanded an adequate supply of sugar beets. In central Colorado[40] and western Nebraska, this was provided substantially by Germans from Russia who were already expert at sugar beet farming when they immigrated in large numbers circa 1890–1905.[41] The United States now also began to catch up with Europe in research. The work of Rachel Lloyd at the University of Nebraska in the late 1880s resulted in a large production increase in the state of Nebraska.[42]

By 1914, the sugar beet industry in the US matched the production of its European counterparts. The largest producers of beet sugar in the US were California, Utah, and Nebraska until the outbreak of World War II.[43][44] In California, Japanese Americans were an important constituent in farming and production. When they were interned during World War II, California's beet sugar production stalled, and was largely shifted to inland states such as Idaho, Montana, North Dakota, and Utah. In many of the regions where new sugar beet farms were started during the war, farmers were unfamiliar with beet sugar cultivation, so they hired Japanese-American workers from internment camps who were familiar with sugar beet production to work on the farms.[45]

In 1935, the inputs required to process 1 short ton (2,000.00 lb; 907.18 kg) of beets to sugar was outlined as follows:[46]

• 80 pounds (36 kg) limestone
• 250 pounds (110 kg) coke (to convert limestone to quicklime)
• 2,500 US gallons (9,500 L; 2,100 imp gal) water

Sugar beets are grown in 11 states and represent 50-55% of the US domestic sugar production.[47] Sugarcane accounts for about 45% of US domestic sugar production. In 1995 sugarcane was grown commercially in Florida, Hawaii, Louisiana, Texas, and Puerto Rico.[48][49] In 2016 the last sugar plantation and mill of Hawaii closed down.[50]

The sugar factory of Allscott, closed down in 2006

Before World War I, the United Kingdom with its far-flung empire, simply imported raw sugar from the cheapest market. The first sugar beet processing factory became operational at Lavenham in Suffolk in 1869.[51] It failed, probably because it lacked the government support that its counterparts on the continent received. By the end of the century sugar production had ceased and the factory was re-purposed as a store house for horse hair and matting. It was totally destroyed by fire in 1905 and today, no trace remains.

The Dutch built the first successful factory at Cantley in Norfolk in 1912, and it was moderately successful since, because of its Dutch backing, it received Dutch bounties.[26] Sugar beet seed from France was listed in the annual catalogues of Gartons Agricultural Plant Breeders from that firm's inception in 1898 until the first of their own varieties was introduced in 1909.

When World War I created a shortage in sugar, it prompted the development of domestic sugar production. In 1915, the British Sugar Beet Society was formed to create an example of a domestic sugar beet industry for the purpose of obtaining government financing which was delivered by the British Sugar (Subsidy) Act 1925. The sugar beet industry in the United Kingdom was finally subsidized, providing stability to the domestic industry that had experienced volatile shifts in profits and losses in the years since 1915.[26] In the 1920s 17 processing factories were built. The British Power Alcohol Association was founded in 1924 to promote the use of beet for fuel.[52]

In 1936, the British sugar beet industry was nationalized in the form of the British Sugar Corporation; this later returned to private ownership becoming British Sugar the sole beet processor in the UK. Following concentration of processing at a few sites by 2009 there were four sugar factories in the United Kingdom (three in East Anglia and one in East Midlands). The Wissington factory is the largest in Europe by amount of sugar beet processed (3 million tonnes) a year.[53]

References to the sugar manufacturing from beets in Russia date back to 1802. Jacob Esipov built the first Russian commercial factory producing sugar from beets in the Tula Oblast.[54][55] During the Soviet period, some particularly impressive advancements were made in seed development, of which the most useful was the development of frost-resistant sugar beet, further expanding the growing range of the sugar beet.[56]

There were various attempts, after 1865, to farm sugar beets in the Australian colony, later state, of Victoria. An industry was established in the district around Maffra in 1896. It became unprofitable due to a drought in 1899 and the factory was taken over by the Victorian government. It was reopened in 1910 and the industry flourished during the inter-war years. Production peaked in 1939–1940. The Second World War affected the industry by taking away its labour force. After the war ended, local farmers preferred dairying to labour-intensive and less-profitable sugar beet production, and the factory closed in 1948. It was the only significant sugar beet factory in Australia.[57] Australia continues to be a major sugar producer, but all production is from sugar cane grown in Queensland and northern New South Wales.[58]

Sugar beet is widely grown in New Zealand as cattle feed, and this practice has spread to some parts of Australia.

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